The gates at the London Avenue Canal were opened around 2 a.m. today after the water level in the canal reached safe levels, according to the U.S. Army Corps of Engineers.

Scott Threlkeld/The Times-Picayune archiveRandy Faherty of the U.S. Army Corps of Engineers checks the water level after dropping the flood gates Saturday, September 12, 2009, at the London Avenue Outfall Canal structure.The corps closed the gates Monday at 2:30 p.m. after water inside the canal reached its "operational trigger" of 2.5 feet and rising as Tropical Storm Ida churned in the Gulf.

When the gates are closed, the corps can pump water from the canal into the lake. The corps' pumps have a combined capacity of 5,200 cubic feet per second.

The London Avenue Canal has a lower "safe water elevation" -- 5 feet -- than New Orleans' other major outfall canals, the 17th Street Canal and the Orleans Avenue Canal. Those canals have "safe" levels of 6 feet and 8 feet, respectively.

The reason for the difference is that there have been questions raised about the floodwalls and the soils along the London Avenue Canal.